This invention relates generally to pneumatic percussive drills, and more particularly to air distributors in valveless, percussive air drills.
Valveless percussive air drills consist basically of a main housing, a reciprocal piston in the housing, a bearing supporting the piston and an air distributor that distributes air via various passageways to activate the piston between a drive stroke and a return stroke. As the drill operates, the piston reciprocates due to the cycling of air pressure differentials across the head of the piston. The alignment of the piston in such a device consists of three bearing points of contact for the piston: contact with the air distributor, contact with the housing and contact with the bearing. This three point contact demands extremely high manufacturing tolerances in order to assure proper function characteristics of the cycle.
Misalignment of any one these components may cause premature failure of the drill because of the loss of alignment of three contact points spaced along the length of the longitudinal axis of reciprocation of the piston. This condition is made more difficult because the piston has an elongated tail stem that can exaggerate any misalignment problems during the cycle.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative provided including features more fully disclosed hereinafter.